Early development of motors dates back to the mid 1800's when pioneer inventors such as Thomas Davenport developed the first real electric motor. Prior to that, early motion devices were created by electrical scientists such as Michael Faraday and Joseph Henry. Although the early development of motors could only create spinning disks or levers, they were important discoveries and built a foundation for development of better motors for the future generations. The development of electric motors leads to advancements in other electrical devices such as generators as well. In the late 1800's, pioneers of the generator figured out that running a motor backwards could create pulses of electricity and this lead to future development of generators to replace batteries as an energy source since batteries were not an economical way to power the needs of society.
Modern electric motors can be powered by either alternating current (AC) or direct current (DC). Originally, DC motors were developed and still to this day use the power of the electromagnetic field. AC electric motors use electromagnetic induction. With electromagnetic induction, an electromagnetic force across a conductor is exposed to a time varying magnetic field and when a magnet is moved toward a conductor, an electromotive force is created. For the material used in these motors, insulated copper wires are most common and wound around a core to create and receive electromagnetic energy in both DC and AC motors. Copper's exceptional current carrying capacity and excellent conductivity makes it the element most commonly used in electrical wiring and electromagnetic energy generation not only in all small motors, but large generators as well. In addition, the strength of a motor varies upon voltage and the length of the wire coils. The longer the wire coils, the larger the electromagnetic field, hence the more to power to turn the rotor.
Although today, with the advancement of motor technology and creating more energy efficient motors, most motors still share some similar parts. The majority of motors contain a stator or an electromagnet which can be wound with insulated wires. A rotor coupled with a shaft sits in the middle of the motor and is exposed to the electromagnetic field created by the electromagnet or stator. To rotate the shaft, its poles are attracted and repelled by the poles of the electromagnets or stator. Motor efficiency is critically measured and the efficiency is calculated by the power that the motor produces. The heat lost during operation of a motor reduces the power output of the motor.
When analyzing DC motors in particular, there are many different types of DC motors and yet two of the more common ones are brushed and brushless DC motors. With brushed DC motors, brushes are hooked up to an external power source and charge a commutator inversely in polarity to a permanent magnet. This causes an armature to rotate within an electromagnetic field. Brushed motors are used in several applications and the speed of the motor is easily controlled with the level of voltage applied. Further, a unique style of a motor which is called a pancake style motor can use fibers to brush along the current when initially providing power to an electric motor. Pancake style motors were originally designed in the 1950's and the brushed Pancake motor evolved from the original printed armature concept. Today, the design has an ironless disc with coils using copper instead of printed circuit board. As the disc spins, the brushes are in direct contact with the copper conductors and this removes the need for a commutator. A magnetic field allows the disc to rotate which is produced by permanent magnets in the rear and front end plates which enables the lines of flux to pass and return through the armature coils. An example of a pending patent for a pancake electric motor is described in U.S. Pat. No. 8,373,319. In this design, the construction of circuits is by phase buses for carrying large currents in the motor or generator and the details of the design are described. Further, the invention explains some of the basic principles of the pancake generator with the advantages of the design compared to standard motors.
With the growing need for more energy efficient power generators, a high efficiency motor for energy and cost savings is needed now more than ever. And to advance on current pancake style electric motor designs such as U.S. Pat. No. 8,373,319, a high torque electric motor with multiple stages of power production can greatly benefit a society that highly depends on electricity.